Apparatus for detecting defects

ABSTRACT

An apparatus for detecting defects in a railway rail includes a search unit and preferably a roller search unit (“RSU”) mounted on a test vehicle and in rolling contact with the running surface of the rails to inspect each rail. The RSU includes a tire filled with a liquid and a transducer assembly mounted within the tire. The transducer assembly includes one or more arrays of ultrasonic transducers directed toward the running surface of the rail. A laser profiler mounted on the test vehicle in combination with a linear encoder provide profile data which is communicated to a system controller to dynamically adjust the focal laws for the one or more arrays of transducers to dynamically steer the transmitted beams to produce the ideal inspection beam sets while the test vehicle is in motion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of application Ser. No. 61/526,094,filed on Aug. 22, 2011, entitled ULTRASONIC INSPECTION SYSTEM.

FIELD

The present invention generally relates to an apparatus for detectingdefects in a structure and, more particularly, to a mobile apparatus forperforming nondestructive-type testing in situ using ultrasonictransducers to detect flaws and defects in a railway rail.

BACKGROUND

The United States Federal Railroad Administration has publishedstatistics which indicate that train accidents caused by track failuresincluding rail, joint bar and anchoring resulted in approximately 1,300derailments from 2001 to 2011. The primary cause of these track failureswas defects and fissures in the rail head.

During their normal use and as would be expected, the rail portions ofmost track structures will be subjected to severe, and uncontrollableenvironmental conditions. These severe environmental conditions, over arelatively long period of time, may ultimately result in such raildeveloping certain detrimental flaws.

In addition, in today's modern railroad industry, the rail portion ofsuch track structures will quite often be required to support ratherheavy loads being carried by modern freight cars. Furthermore, theseheavy loads are travelling at relatively high speeds. It would not beuncommon for these freight cars, when they are fully loaded with cargo,to weigh up to generally about 125 tons. Such relatively heavy loads andhigh speeds can, also, result in undesirable damage to such railportions of the track structure. Such damage, for example, may includestress fractures.

It would be expected, therefore, that if these detrimental defects werenot timely detected and, likewise, if they are left unrepaired suchdefects could lead to some rather catastrophic disasters, such as, atrain derailment.

As is equally well known, such train derailments are not only costly tothe railroad industry from the standpoint of the damage that will likelybe incurred to both the cargo being transported and to the railwayequipment itself, but, even more importantly, such train derailments mayalso involve some rather serious injuries, or even worse death, torailway personnel and/or other persons who may be in the vicinity of atrain derailment.

It is further well known that a relatively large number of these trainderailments have resulted in the undesirable and often costly evacuationof nearby homes and businesses. Such evacuation may be required, forexample, when the cargo being transported involves certain highlyhazardous chemical products. These hazardous chemical products willgenerally include both certain types of liquids, such as corrosiveacids, and certain types of toxic gases, such as chlorine.

To detect such flaws and defects, ultrasonic testing has been employed.Vehicles have been built which travel along the track and continuouslyperform ultrasonic testing of the track. These vehicles carry test unitswhich apply ultrasonic signals to the rails, receive ultrasonic signalsback from the rails, and provide indications of flaws and defects.

Some of these systems employ small, thin-walled tires which roll alongthe rails. They are pressed down against the rail so as to have a flatarea in contact with the rail. These tires contain acoustic transducersand are filled with a liquid, usually a water-glycol solution. Thetransducers are arranged at various angles to produce acoustic beamswhich travel through the mounting substrate and liquid and are directedtoward the rail surface. The angles are predetermined based on the knowngeometry of a new rail. The high frequency electrical transducers arepulsed with energy and the generated beams pass through the material ofthe liquid and tire into the rail. The angle of incident of the beamwith respect to the rail surface is predetermined based on the desiredangle of refraction in a known material, assuming a horizontal headshape according to Snell's law.

Only a few transducers can be mounted to the substrate due to spatialconsiderations. Also, the angles of the acoustic beams produced by thetransducers are dictated by their fixed mounting angle. The rail headmay be worn or deformed by the massive loads and stresses to which it issubjected. The shape of the rail head may change over time whereby therunning surface of the rail head is no longer substantially horizontal.Because many of the inspection systems employ ultrasonic transducersmounted in a fixed position at a fixed angle relative to a presumedhorizontal inspection surface, the resulting beam inspection angles maynot be optimal and may fail to detect defects in the rail.

SUMMARY

The present invention provides an apparatus for detecting defects in arailway rail. The apparatus includes a search unit and preferably aroller search unit (“RSU”) mounted on a test vehicle and in rollingcontact with the running surface of the rails to inspect each rail. TheRSU includes a tire filled with a liquid and a transducer assemblymounted within the tire. The transducer assembly includes one or morearrays of ultrasonic transducers directed toward the running surface ofthe rail. The liquid provides a coupling between the transducers throughthe tire wall and into the rail. Beams transmitted by the one or morearrays of ultrasonic transducers may be dynamically adjusted tocompensate for the varying profile of the rail head and running surface.A laser profiler mounted on the test vehicle in combination with alinear encoder provide profile data which is communicated to a systemcontroller to dynamically adjust the focal laws for the one or morearrays of transducers to steer the transmitted beams to produce theideal inspection beam sets while the test vehicle is in motion.

The ultrasonic phased array transducers including one or more transducerassemblies with 8 to 256 individual elements that are individuallycontrolled may be used to effectively steer the inspection beam. Theelements may be arranged in a strip (linear array), a square matrix (2-Darray), a ring (annular array), a circular matrix (circular array), orother more complex shapes.

An ultrasonic phased array transducer system varies the time between thepulsing of individual elements of the array in such a way that theindividual waves from each individual element combine in predictableways to steer or shape the beam emitted from the array. This isaccomplished by pulsing the individual elements at calculated times.Based on the focal law of the array, the properties of the transducerassembly, the transmission medium and the geometry and acousticalproperties of the test material, the beam can be dynamically steeredthrough various angles and focal distances. Beam steering isaccomplished in a fraction of a second allowing the beam to be steeredto the optimal angle based on the orientation of the test material, suchas a rail head, to scan from multiple angles, sweep over a range ofangles, or scan at multiple focal depths. The ultrasonic phased arraytransducer can spatially sort a returning wave front according to thearrival time and amplitude at each element to be processed anddisplayed.

The output from profiling sensors such as one or more laser transceiversor cameras are combined to determine the geometric profile of the rail,which is used by the system to determine the focal laws for the desiredtarget of the ultrasonic beams generated by the ultrasonic phased arraytransducers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of a test vehicle with an ultrasonicinspection system of the present invention.

FIG. 2 is a diagrammatic illustration of a rail profiler system.

FIG. 3 is a partial plan view of a rail head.

FIG. 4 is a sectional end view of a rail.

FIG. 5 is an illustration of two-dimensional profile data for a rail.

FIG. 6 is a perspective view of a right carriage assembly.

FIG. 7 is a perspective view of the carriage assembly.

FIG. 8 is a partial sectional view of a first RSU assembly.

FIG. 9 is a partial sectional view of a second RSU assembly.

FIG. 10 is a perspective view of a phase array ultrasonic transducerassembly.

FIG. 11 is a plan view of the phased array ultrasonic transducerassembly of FIG. 10.

FIG. 12 is a perspective view of a phased array ultrasonic transducerfrom the assembly of FIG. 10.

FIG. 13 is an illustration of beams generated from the ultrasonic phasedarray assembly of FIG. 11.

FIG. 14 is a plan view of an ultrasonic transducer assembly.

FIG. 15 is a sectional view of the ultrasonic transducer assembly ofFIG. 14 along line 15-15.

FIG. 16 is a plan view of an ultrasonic transducer assembly.

FIG. 17 is an illustration of beams generated by phased array ultrasonictransducers for a worn rail head.

FIG. 18 is an illustration of beams generated by phased array ultrasonictransducers for a rail head.

FIG. 19 is an illustration of beams generated by phased array ultrasonictransducers for a worn rail head.

FIG. 20 is an enlarged partial sectional view of a worn rail headillustrating a defect.

FIG. 21 is an enlarged partial sectional view of a worn rail headillustrating another defect.

DESCRIPTION

As required, detailed embodiments of the present invention are disclosedherein. However, it is to be understood that the disclosed embodimentsare merely exemplary of the invention that may be embodied in variousand alternative forms. The figures are not necessarily to scale; somefeatures may be exaggerated or minimized to show details of particularcomponents. Therefore, specific structural and functional detailsdisclosed herein are not to be interpreted as limiting, but merely as arepresentative basis for the claims and/or as a representative basis forteaching one skilled in the art to variously employ the presentinvention.

Moreover, except where otherwise expressly indicated, all numericalquantities in this description and in the claims are to be understood asmodified by the word “about” in describing the broader scope of thisinvention. Practice within the numerical limits stated is generallypreferred. Also, unless expressly stated to the contrary, thedescription of a group or class of materials as suitable or preferredfor a given purpose in connection with the invention implies thatmixtures or combinations of any two or more members of the group orclass may be equally suitable or preferred.

Referring initially to FIGS. 1 and 2, a rail inspection apparatus unitis generally indicated by reference numeral 20. The rail inspectionapparatus includes a carriage 22 for supporting test assemblies 24mounted behind a test vehicle 26, a profiler system 28 mounted under thetest vehicle 26, and an encoder 30, all of which are coupled to a systemcontroller 32 mounted inside the test vehicle 26.

The test vehicle 26 includes front 34 and rear 36 rubber tires andflanged rail wheels 38 and 40. The flanged rail wheels 38 and 40 engagerails 42, 44 when the test vehicle 26 is in a hi-rail configuration. Inthe hi-rail configuration the front tires 34 are not in contact with theground or rails 42 and 44, and the front of the test vehicle 26 issupported on the front flanged rail wheels 38. The rear tires 36 are incontact with the rails 42 and 44 to drive the test vehicle 26 along therails 42 and 44. The encoder 30 is coupled to the front flanged railwheels 38.

The encoder 30 outputs information to the test assemblies 24 andprofiler system 28, which is used to determine position. The encoder 30is preferably a linear encoder that outputs a digital signalcorresponding to the rotation of the flanged rail wheel 38. The encoder30 outputs a signal which corresponds to the rotation of the rail wheel38, which in turn is used to calculate the position of the test vehicle26.

Referring to FIGS. 1 and 2, the profiler system 28 includes two pairs oflaser transceivers 46 and 48, and may also include two pairs of linescan cameras 50 and 52, each of which is directed at rails 42 and 44,respectively. The laser pair 46 includes a gauge side laser transceiver54 and a field side laser transceiver 56 directed at rail 42. Gauge sidelaser transceiver 54 scans the gauge side 58 of the rail 42, includingthe web and base, across the rail head 60. The field side lasertransceiver 56 scans the field side 62 of the rail 42, including the weband base, across the rail head 60. Likewise, laser transceiver pair 48includes a gauge side laser transceiver 64 and a field side lasertransceiver 66 directed at rail 44. Gauge side laser transceiver 64scans the gauge side 68 of the rail 44, including the web and base,across the rail head 70. The field side laser transceiver 66 scans thefield side 72 of the rail 44, including the web and base, across therail head 70. Each laser transceiver may scan at a fixed rate orfrequency or may be triggered by the encoder 30 output. A laserprofiling system such as a LMI Gocator 2050 available from LMITechnologies may be used.

Line scan camera system 50 includes a gauge side line scan camera 76 anda field side line scan camera 78 directed at rail 42. The gauge sideline scan camera 76 captures a line or column of data of the gauge side58 of the rail 42. The field side line scan camera 78 captures a line orcolumn of data of the field side 62 of the rail 42. Likewise, the linescan camera system 52 include a gauge side line scan camera 80 and afield side line scan camera 82 directed at rail 44. The gauge side linescan camera 80 captures a line or column of data of the gauge side 68 ofthe rail 44 while the field side line scan camera 82 captures a line orcolumn of the field side 72 of the rail 44. Line scan cameras such as aBasler Runner series available from Basler Vision Technologies may beused.

Each of the line scan cameras 76, 78, 80 and 82 may be triggered by theencoder 30 output or scan at a set frequency such as 27,000 Hz,depending on the hardware selected and the storage capacity of thesystem. It should be understood that other frequencies and resolutionsmay be used for the line scan cameras and laser transceivers.Additionally, other image systems may be used such as a high definitionvideo system, for example.

The pair of laser transceivers 46 and line scan cameras 50 may besurrounded by a housing 84. Laser transceivers 48 and line scan cameras52 may be surrounded by a housing 86. Each housing 84 and 86 enclosesthe laser transceivers and line scan cameras on the four vertical sidesand top to protect the lasers and cameras from the environment, toimprove the performance of the lasers and cameras in all ambientlighting conditions and to protect the eyes of any individuals workingor located around the test vehicle 26.

Referring to FIGS. 6-9, the carriage assembly 22 includes right 100 andleft 102 carriages. The right 100 and left carriages 102 are connectedtogether by a cross member 104, which includes a pneumatic or hydrauliccylinder 106 to adjust the width of the carriage 22 as necessary toengage the rails 42 and 44. The left carriage 102 is a mirror image ofthe right carriage 100 so only the right carriage will be described indetail, it being understood that the same detailed description appliesto the left carriage 102.

The right carriage 100 includes a pair of flanged rail wheels 107, whichsupport the carriage 100 on the rail 42. The flanged rail wheels 107 aremounted to a frame 109, to which a first roller search unit (“RSU”)assembly 108 and a second RSU assembly 110 is mounted. Nylon, Teflon® orother high density polymer blocks 112 are mounted between the flangedrail wheels 107 and the RSUs 108 and 110. Spray nozzles 114 are mountedin the polymer blocks 112 and directed toward the running surface of therail head 60 and the adjacent RSU 108 or 110. The polymer blocks 112provide protection for the RSUs 108 and 110. The spray nozzles 114 spraya liquid such as water or a water/ethylene glycol mixture on the runningsurface of the rail head 60 to remove debris and to improve the contactof the RSUs 108 and 110 with the running surface 69 of the rail 42.

RSU assembly 108 includes a tire 120 mounted on a wheel 122, whichrotates with the tire 120 about an axle 124. The tire is clamped to thewheel 122 at its bead 121 and includes a circumferential contact surfaceor tread 123, which makes contact with the running surface 69 of therail head 60. The axle 124 is mounted to the frame 109. The tire 120contains a coupling liquid 126 such as a water/ethylene glycol mixture.A transducer assembly 128 may be positioned within the tire 120 andcoupled to the axle 124. The transducer assembly 128 includes a lowerplanar surface 129, which is mounted facing the circumferential contactsurface 123 of the tire 120, and is maintained in a plane generallyparallel to the running surface 69 of the rail head 60 at a fixeddistance.

RSU assembly 110 includes a tire 130 mounted on a wheel 132, whichrotates with the tire 130 about an axle 134. The axle 134 is mounted tothe frame 109. The tire is clamped to the wheel 132 at its bead 131 andincludes a circumferential contact surface or tread 133, which makescontact with the running surface 69 of the rail head 60. The tire 130contains a coupling liquid 136 such as a water/ethylene glycol mixture.A transducer assembly 138 may be positioned within the tire 130 andcoupled to the axle 134. The transducer assembly 138 includes a lowerplanar surface 139, which is mounted facing the circumferential contactsurface 133 of the tire 130, and is maintained in a plane generallyparallel to the running surface 69 of the rail head 60 at a fixeddistance.

Referring to FIGS. 9-13, the transducer assembly 128 includes atransducer mount 140, which may be formed from a high strength plastic,epoxy, resin, Noryl® resin blend of polyphenylene oxide and polystyrene(“PPO”), polyphenylene ether (“PPE”) resin, or a PPE/olefin resin blend,for example.

Conventional ultrasonic transducers typically consist of a singletransducer that generates and receives ultrasonic sound waves, or a pairof transducers, one generating sound waves and the other receiving theecho returns. Phased array transducers typically include a transducerassembly with 8 to 256 individual elements that are individuallycontrolled. The elements may be arranged in a strip (linear array), asquare matrix (2-D array), a ring (annular array), a circular matrix(circular array), or other more complex shapes. The transducerstypically operate at frequencies from 1 MHz to 10 MHz, for example.

The ultrasonic phased array transducer system varies the time betweenthe pulsing of individual elements of the array in such a way that theindividual waves from each individual element combine in predictableways to steer or shape the beam from the array. This is accomplished byselectively energizing or pulsing the individual elements at independenttimes. These respective delays are referred to as delay laws and/orfocal laws. Based on the focal law of the array, the properties of thetransducer assembly mount, the transmission medium and the geometry andacoustical properties of the test material, the beam can be dynamicallysteered through various angles and focal distances. Beam steering isaccomplished in a fraction of a second allowing the beam to be steeredto the optimal angle based on the orientation of the test material, suchas a rail head, to scan from multiple angles, sweep over a range ofangles, or scan at multiple focal depths. The ultrasonic phased arraytransducer can spatially sort a returning wave front according to thearrival time and amplitude at each element to be processed anddisplayed.

The transducer assembly 128 includes four ultrasonic phased arraytransducers 142, 144, 146 and 148 secured to the mount 140 forgenerating ultrasonic acoustic beams forward and backward longitudinallygenerally parallel to a longitudinal axis X of the rail 42 and acousticbeams across the rail 42 at an angle relative to the longitudinal axis Xfrom both the gauge side 58 and the field side 62 to detect under shelldefects. The transducer assembly 128 also includes two ultrasonic phasedarray transducers 150 and 152, secured to the mount 140, directedlaterally or transversely relative to a lateral axis Y across the railhead 60 from both the gauge side 58 and field side 62, to detectvertical split head (“VSH”) defects.

The forward facing ultrasonic phased array transducers 142 and 146 aremounted on the transducer mount 140 on a compound symmetric wedge shapewherein surface 154 is formed or cut at two different angles, forexample, a wedge angle 156 and a roof angle 158. Wedge angle 156 may bebetween zero and 30 degrees and roof angle 158 may be between 10 and 55degrees, for example. The backward facing ultrasonic phased arraytransducers 144 and 148 are symmetrically secured to the transducermount 140 at the same angles as the corresponding forward facingultrasonic phased array transducers 142 and 146. The laterally facingultrasonic phased array transducers 150 and 152 are secured to thetransducer mount 140 at a roof angle of between about 10 and 55 degreesand a wedge angle of between about zero and 30 degrees, for example. Forclarity, the ranges stated herein are stated as positive ranges, but itshould be understood that a range includes a corresponding negativerange or +/− a range.

In the exemplary embodiment, ultrasonic phased array transducers 142 and146 are secured to transducer mount 140 such that beams 160 and 162,when viewed from above, are emitted parallel to rail 42 and when viewedin elevation view are emitted at an angle to produce a resultant beam inthe rail 42 of about 60 to 80 degrees from vertical. Likewise,ultrasonic phased array transducers 144 and 148 emit beams 164 and 166parallel to rail 42 in the opposite direction from beams 160 and 162when viewed from above, and at an angle to produce a resultant beam inthe rail 42 of about 60 to 80 degrees from a vertical axis Z when viewedin elevation.

Ultrasonic phased array transducers 142 and 146 also emit ultrasonicbeams 168 and 170 directed generally parallel to rail 42 when viewedfrom above, each crossing the rail 42 in opposite directions at an angleto produce a resultant beam in the rail 42 of about 10 to 30 degrees.When viewed in elevation view, beams 168 and 170 descend into rail 42 atan angle to produce a resultant beam in the rail 42 of about 60 to 80degrees from vertical. Likewise, ultrasonic phased array transducers 144and 148 also emit beams 172 and 174 directed generally parallel to rail42 when viewed from above, each crossing the rail 42 in oppositedirections at an angle to produce a resultant beam in the rail 42 ofabout 10 to 30 degrees. When viewed in elevation view, beams 172 and 174descend into rail 42 at an angle to produce a resultant beam in the rail42 of about 60 to 80 degrees from vertical. Ultrasonic beams 168, 170,172 and 174 provides a view of under shell defects in the rail head 60from both the gauge side 58 and the field side 62.

Ultrasonic phased array transducers 150 and 152 emit ultrasonic beams176 and 178 which are directed downward at an angle to produce aresultant beam in the rail 42 of approximately 30 to 80 degrees tovertical when viewed in a transverse elevation view. Ultrasonic phasedarray transducers 150 and 152 may be longitudinally offset to avoidinterference between the generated beams 176 and 178. Beam 176 entersrail head 60 on the gauge side 58 and travels across head 60 to thefield side 62. Beam 178 enters rail head 60 on the field side 62 andtravels across head 60 to the gauge side 58. Beams 176 and 178 detectvertical split head defects. Additionally, ultrasonic phased arraytransducers 150 and 152 may induce a shear beam, compression beam, orboth in the head 60 depending on the rail head shape constraints.

Referring to FIGS. 8 and 14-16, the transducer assembly 138 includes atransducer mount 200 formed from a Noryl® resin blend or other resin.The transducer assembly 138 may include individual ultrasonictransducers or one or more ultrasonic phased array transducers, directedat the rail 42. Preferably, transducer assembly 138 includes a bank offorward-directed ultrasonic transducers 202 and rearward-directedultrasonic transducers 204 mounted at an angle to produce a beam in therail of approximately 30 to 60 degrees to vertical in oppositedirections. As illustrated, banks 202 and 204 each include fourultrasonic transducers 206, 208, 210, 212, 214, 216, 218, 220, althoughfewer or more ultrasonic transducers may be used. Each of the ultrasonictransducers 206-220 may be energized independently to emit aforward-directed beam 222 and a rearward-directed beam 224. Beams 222and 224 penetrate through the web 61 of the rail 42 to the foot 63 todetect defects, such as web and bolt hole cracks, weld defects andcentrally located transverse defects. The transducers selected to fireare determined by the rail geometry and known mount alignment, whichapplies to each bank of ultrasonic transducers.

The transducer assembly 138 may also include conventional transducers226 and 228, which may be mounted along a longitudinal centerline oftransducer mount 200 to produce a refracted sheer wave of about 55 to 85degrees. The transducers 226 and 228 may be energized to produceultrasonic beams 230 and 232 at an angle to produce a resultant beam inthe rail 42 of approximately 60 to 80 degrees relative to vertical axisZ in opposite directions generally parallel to longitudinal axis X.Beams 230 and 232 detect transverse defects along the transverse axis Yof the rail head 60.

Transducer assembly 138 may include an additional ultrasonic transducerbank 234 mounted at an angle of zero degrees to emit beam 236substantially vertically through the web 61 to the foot 63. Beam 236detects defects such as bolt-hole cracks, centrally located defects aswell as rail head 60 horizontal and angled defects. The ultrasonictransducers in bank 234 typically operate in pairs of adjacentultrasonic transducers with one ultrasonic transducer emitting the beam236 and the other ultrasonic transducer receiving the beam reflection.This pitch/catch combination reduces false returns from internalreflections within the RSU and reflections from the surface of the rail.

The pair of ultrasonic transducers in bank 234 is tightly spaced and maybe transversely arranged as illustrated in FIG. 14 or may belongitudinally arranged in a stepped pattern as illustrated in FIG. 16.

To calculate the focal law for each ultrasonic phased array transducer,raw cross section points are determined by the laser transceivers 46 and48. For simplicity and clarity, the process for one of the transversepair 46 will be discussed, which will also apply to the othertransceiver pair 48.

Referring to FIGS. 2-5, data is received by each of the lasertransceivers 54 and 56, which are directed at rail 42. The data pointsare sent to the system controller 32 along with the encoder data fromencoder 30. Each set of data points from the laser transceiversrepresents a slice of the rail 42 at a given encoder count. The systemcontroller 32 takes the raw data points from each laser transducers 54and 56 for a given encoder count and processes the points to produce atwo-dimensional slice of the rail 42 (see FIG. 4). From thetwo-dimensional slice, the system controller may determine rail featuressuch as the head 60, web 61, foot 63, gauge surface of the head 65, thefield surface of the head 67, the running surface 69, the gauge corner71, the field corner 73, the gauge side web surface 75 and the fieldside web surface 77, for example, as well as the feature position andgauge of the rail. Additionally, extraneous material layers such astrack structures (i.e. spikes, joint bars, etc.) and other layers suchas weeds, and debris are identified and filtered out. Surface normalsare calculated and smoothed through interpolation, averaging and planesegment reduction.

Based on the transducer assembly 128 and orientation of each individualultrasonic transducer array, a range of steering angles is iterativelycalculated using ray tracing techniques for each transducer array foreach slice 74 of the rail 42, or at a predetermined interval based ontime or travel.

For example, for a given ultrasonic transducer array, a trial steeringangle is selected for an element within the array. The acousticinterface collisions (time and position) are calculated. Using Snell'slaw, the refraction or reflection angles are calculated at the interfacefor a known material, such as steel. The surface normal and acousticvelocities in the material are used to calculate the refraction angle.This calculation is repeated for all interfaces. Next, a targetcollision is calculated and given a score based on the target proximityand orientation. This process may be repeated for all angles and allelements of the transducer array. The target score determines theselected ray for a given element. Algorithms such as binary ray searchmay be used to improve processing time or improving the acoustic beam.

For each element of a given array, a total time travel to a commontarget point is calculated. The travel time for each element is comparedto compute the relative delay in firing or energizing each element andreceive digitizing delay to steer the resultant beam to the targetpoint. For each profile slice of the rail, or at a fixed time interval,the focal laws are recalculated and compared to the focal laws for theprevious profile slice of the rail. If the new focal laws are differentthan the current applicable focal law, the new focal law may be applied.The difference may be determined on a profile slice-by-profile slicebasis, or for calculations falling outside a tolerance or range for thecurrent applicable focal law. In this manner, the beam generated by theultrasonic transducer array compensates for variations in the runningsurface 69 of the rail and the resultant effect on the angle ofrefraction.

For the transducer assembly 138, profile information is used todetermine which transducers to fire for any given profile slice. Forexample, considering transducer bank 202, the beam 222 generated by anyof the transducers 206-212, is oriented to penetrate the web 61 of therail 42 and travel to the foot 63. If no return signal is received, thenno defect has been detected. However, in order for the beam 222 topenetrate through the web 61 to the foot 63, the angle of incidence ofthe beam 222 relative to the surface 69 of the rail head 60 generallyshould be in a longitudinal plane (Y-Z axes) perpendicular to the plane(X-Z axes) of the running surface 69 and along the centerline 81 of theweb 61. If the running surface 69 is not in a horizontal plane or theweb 61 is not oriented along the theoretical centerline of a new rail,the beam 222 may “miss” the web 61 and not penetrate to the foot 63.

To compensate for rail wear and variations prevalent in the field with aworn or damaged rail, profile data is used to determine which of thetransducers 206-212 will be fired for any given profile slice.Typically, transducers 208 or 210 will likely be fired.

Determination of which of the transducer pairs in the transducer bank204 and 234 is also based on profile information and calculation of theincident angle which will penetrate the web 61.

Referring to the FIGS. 1-3, and 17-21, as the test vehicle 26 travelsalong the rails 42 and 44, the laser profiling system 28 scans the rails42 and 44 and the data is output to the system controller 32. A 2-Dprofile 74 is generated for each output from the encoder 30 or at apredetermined frequency, and the geometry of each slice 74 isdetermined. The geometry information is used by the system controller 32to dynamically calculate the optimal incident angle of a particularultrasonic beam with respect to the rail head surface and steer the beambased on Huygen's principle and the focal laws. A steering angle foreach transducer array may be calculated for each slice 74 orperiodically. The calculated steering angle may be dynamically appliedfor each profile or may be applied when a profile, which is out of rangeor tolerance for a particular steering angle, persists for two or morecalculated profiles.

A focal law table is maintained by the system controller 32 and storedby encoder count. As the test vehicle travels down the rails whichcorresponds to the longitudinal or X-axis, the ultrasonic transducersystem monitors the encoder count and selects the proper focal laws foreach cycle. The ultrasonic transducer system delays firing of individualultrasonic transducer elements within an array a given amount based onthe applied focal law table, and delays receiving and sampling by thegiven amount for each element. The ultrasonic transducer system sums allelement responses at appropriate time intervals and constructs an ASCANper element group. The ASCAN is sent to the system controller 32 alongwith the encoder data.

The ASCAN data from the ultrasonic transducer system is placed in 3-D byapplying time along with the ray tracing calculated in the focal lawcalculations. The amplitude from the ASCAN may be represented in anumber of ways such as color, transparency, and/or disc size, forexample. The ASCAN data based on the encoder location data is thenrepresented along with the data from the profiler and the imageconstructed from the line scan cameras to optionally present a 3-D imageof the rail with the location of a defect detected within the rail.Additionally, the 3-D image may be viewed by the operator from anyangle, rotating the image as desired, and overlaying camera data toprovide additional information to the operator.

When a relevant indication (defect) is detected, the area of the defectmay be thoroughly inspected by taking advantage of the phased array'scapability to sweep through a range of angles. This can be done in asingle arc for a linear arrangement of phased array elements or inmultiple dimensions for a matrix or other arrangement of phased arrayelements. The system controller 32 calculates focal laws to do atargeted sweep of an area at a higher resolution to verify, size andclassify the defect. Further, two or more arrays of transducers may befocused on a defect to scan the defect from various angles to provideadditional information to better characterize and display the defect.

The rail cross sections illustrated in FIGS. 4 and 5 show a rail profilefor an unworn rail 42 with orientation axes X (longitudinal), Y(transverse) and Z (vertical). The rail cross section illustrated inFIG. 18 shows a rail profile for an unworn rail 400. The rail crosssections illustrated in FIGS. 17 and 19-21 show a rail profile for aworn rail 402. Referring to FIG. 18, for the unworn rail 400, theincident angles of beams 160 and 162 are dynamically adjusted bytransducer arrays 142 and 146 respectively, to produce resultant beams161 and 163.

Referring to FIG. 17, for the worn rail 402, the incident angle of beam160 is dynamically adjusted by transducer array 142 to produce resultantbeam 161. The incident angle of beam 162 is dynamically adjusted bytransducer array 146 to produce resultant beam 163.

Referring to FIG. 19, for the worn rail 402, the incident angle of beam168 is dynamically adjusted by transducer array 142 to produce resultantbeam 169. The incident angle of beam 170 is dynamically adjusted bytransducer array 146 to produce resultant beam 171. Because of the wornrail head 406 on the gauge side 408 of the rail head 406 the angle ofincident (the primary steering angle) is adjusted by steering the beamto achieve the desired angle of refraction in the rail head 406.

If a defect 410 or 412 for example, is detected, information such as thecharacteristics of the defect, location, image information at thelocation of defect, and geometry of the defect may be stored.Additionally, the system controller 32 may direct one or more phasedarray transducers in the second or additional trailing RSUs to scan orsweep the area of a defect detected by the first RSU 108 to obtainadditional information regarding the defect. The defect location in thehead, or anywhere a defect is located, may be displayed graphicallyalong with the profile and line scan camera data to provide the operatorwith a 3-D image that may be manipulated, rotated and viewed from anyorientation or angle. The defect may be viewed from any vantage pointoutside the rail or may be viewed from within the rail. The size of thedefect 410 or 412, for example, may be represented by concentric ringsaround the defect or by colors to provide additional information to theoperator.

It is to be understood that while certain now preferred forms of thisinvention have been illustrated and described, it is not limited theretoexcept insofar as such limitations are included in the following claims.

Having thus described the invention, what is claimed as new and desiredto be secured by Letters Patent is as follows:
 1. An inspectionapparatus for inspecting a railway rail comprising: a carriage forsupporting a transducer assembly, a profiler system adapted to outputprofile data corresponding to a profile of the rail, an encoder inrolling contact with the rail and adapted to output an encoder signalcorresponding to rotation of said encoder, said transducer assemblyhaving a first ultrasonic phased array transducer directed toward arunning surface of the rail, a system controller coupled to saidprofiler system to receive profile data therefrom, coupled to saidencoder to receive said encoder signal therefrom, and coupled to saidfirst ultrasonic phased array transducer, said system controllerresponsive to said profile data, and energizing one or more of saidfirst ultrasonic phased array transducer elements to emit an ultrasonicbeam from said first ultrasonic phased array transducer into the rail ata desired angle, wherein said first ultrasonic phased array transducerincludes a roof angle of between 10 and 55 degrees and a wedge angle ofbetween 0 and 30 degrees.
 2. The inspection apparatus of claim 1 whereinsaid profiler system includes first and second laser transceivers, saidfirst laser transceiver directed toward a field side of the rail, andsaid second laser transceiver directed to a gauge side of the rail. 3.The inspection apparatus of claim 1 wherein said first ultrasonic phasedarray transducer emits an ultrasonic beam in a first ultrasonic phasedarray transducer first direction generally parallel to a longitudinalaxis of the rail and at a resultant angle in a known material of about60 to 80 degrees from a vertical axis of the rail.
 4. The inspectionapparatus of claim 1 wherein said first ultrasonic phased arraytransducer emits an ultrasonic beam in a first ultrasonic phased arraytransducer first direction at a first resultant angle in a knownmaterial of about 60 to 80 degrees from a vertical axis of the rail andat a second resultant angle in a known material of about 15 to 35degrees relative to a longitudinal axis.
 5. The inspection apparatus ofclaim 1 wherein said transducer assembly includes a second ultrasonicphased array transducer, said first ultrasonic phased array transducerdirected toward the running surface of the rail at a first ultrasonicphased array transducer first angle, said second ultrasonic phased arraytransducer directed toward the running surface of the rail at a secondultrasonic phased array transducer first angle.
 6. The inspectionapparatus of claim 1 wherein said transducer assembly includes a firstultrasonic transducer directed toward the running surface of the rail ina first ultrasonic transducer first direction.
 7. The inspectionapparatus of claim 6 wherein said first ultrasonic transducer firstdirection is generally parallel to a longitudinal axis to emit anultrasonic beam at a resultant angle in a known material of about 30 to60 degrees from said vertical axis.
 8. The inspection apparatus of claim1 wherein said transducer assembly includes a plurality of ultrasonictransducers directed toward the running surface of the rail in a one ormore directions.
 9. The inspection apparatus of claim 1 wherein saidtransducer includes a first pair of ultrasonic transducers mountedadjacent each other and directed toward said circumferential surface ofsaid tire along said vertical axis, a first one of said first pair ofultrasonic transducers to emit a beam generally parallel to saidvertical axis, a second one of said first pair to receive a reflectionof said beam emitted from said first one of said pair of ultrasonictransducers.
 10. The inspection apparatus of claim 1 wherein transducerincludes a first ultrasonic transducer directed toward saidcircumferential surface of said tire in a first ultrasonic transducerfirst direction generally parallel to a longitudinal axis to emit anultrasonic beam at a resultant angle in a known material of about 60 to80 degrees from said vertical axis.
 11. The inspection apparatus ofclaim 10 wherein said transducer includes a second ultrasonic transducerdirected toward said circumferential surface of said tire in a secondultrasonic transducer first direction opposite said first ultrasonictransducer first direction generally parallel to said longitudinal axisto emit an ultrasonic beam at a resultant angle in a known material ofabout 60 to 80 degrees from said vertical axis.
 12. The inspectionapparatus of claim 1 wherein said first ultrasonic phased arraytransducer receives return data from said emitted ultrasonic beam andsaid system controller combines said return data with said profile dataand encoder data to generate a two dimensional image of a slice of therail and an internal defect from said return data.
 13. The inspectionapparatus of claim 12 wherein said system controller combines two ormore slices to generate a three dimensional image of the rail and saidinternal defect.
 14. The inspection apparatus of claim 1 wherein saidprofiler system includes one or more cameras directed toward the rail tocapture image data, said one or more cameras coupled to said systemcontroller.
 15. The inspection apparatus of claim 14 wherein said firstultrasonic phased array transducer receives return data from saidemitted ultrasonic beam and said system controller combines said returndata with said profile data, said encoder data and said image data togenerate a three dimensional image of the rail and said internal defect.16. The inspection apparatus of claim 14 wherein said one or morecameras is a line camera.
 17. The inspection apparatus of claim 1wherein said first ultrasonic phased array transducer is a linear array.18. The inspection apparatus of claim 1 wherein said first ultrasonicphased array transducer is a square matrix.
 19. The inspection apparatusof claim 1 wherein said first ultrasonic phased array transducer is anannular array.